Reading pane buttons in "New" Outlook

I've spent considerable time searching around but have been unable to find any information on this at all, so hoping someone here knows what's going on.

Occasionally, buttons will appear at the bottom of the Reading Pane on "new" Outlook. I don't know what to call them and have never seen them in any documentation, but I get them all the time...

The leftmost button will change to "Please select a message" if nothing is selected in the list, or "XXX sent a message" where "XXX" is the sender of the message selected in the list.

The right button shown in the screenshot above shows the subject of an email that I was editing a little while ago, but subsequently sent. The message is not open in a new window, but was at one point, though that doesn't seem to make buttons appear here consistently.

My questions are thus:

1. What do I call this area of the screen?

It's completely new AFAIK so perhaps knowing what the area is called will give some pointers as to what these buttons are for

2. What makes these buttons appear?
I can't consistently perform any action to make them appear on command, but they seem to do so frequently without my asking. Sometimes there's two, sometimes more. It must be contextual because restarting Outlook makes them go away.

3. Do I have any control over these?
This area seems like some useful real estate, it would be good to influence which "buttons" appear here, but I don't hold much hope for this as there doesn't seem to be anything in Settings for this